Cytomegalovirus (CMV) infection

Cytomegalovirus (CMV) is a common virus that can infect almost anyone. Most people don't know they have CMV because it rarely causes symptoms. However, if you're pregnant or have a weakened immune system, CMV is cause for concern.

Once infected with CMV, your body retains the virus for life. However, CMV usually remains dormant if you're healthy.

CMV spreads from person to person through body fluids, such as blood, saliva, urine, semen and breast milk. CMV spread through breast milk usually doesn't make the baby sick. However, if you are pregnant and develop an active infection, you can pass the virus to your baby.

There's no cure for CMV, but drugs can help treat newborns and people with weak immune systems.

Symptoms Causes Risk factors Complications Prevention

Newborns infected with CMV in the womb (congenital CMV), babies who become infected during birth or shortly after birth (perinatal CMV) — such as through breast-feeding — and people with weakened immune systems are more at risk of developing signs and symptoms than are healthy adults.

Symptoms in babies

Pregnant women who become infected are at low risk of transmitting the virus to their babies. If it's the first time you've had the infection (primary CMV), risk of transmitting the virus to the baby is higher than it is with reactivated infection. Transmission usually occurs during the first half of pregnancy, usually the first trimester.

Most babies who are infected before they're born appear healthy at birth, but a few develop signs over time — sometimes not for months or years after birth. The most common of these late-occurring signs is hearing loss. A small number may develop vision impairment as well.

Babies with congenital CMV who are sick at birth tend to be very sick. Signs and symptoms include:

  • Yellow skin and eyes (jaundice)
  • Purple skin splotches or a rash or both
  • Small size at birth (or low birth weight)
  • Enlarged spleen
  • Enlarged and poorly functioning liver
  • Pneumonia
  • Seizures

Symptoms in people with compromised immunity

An illness resembling infectious mononucleosis is the most common presentation of CMV in people with weakened immune systems (immunocompromised). CMV also can attack specific organs. Signs and symptoms may include:

  • Fever
  • Pneumonia
  • Diarrhea
  • Ulcers in the digestive tract, possible causing bleeding
  • Hepatitis
  • Inflammation of the brain (encephalitis)
  • Behavioral changes
  • Seizures
  • Coma
  • Visual impairment and blindness

Most people infected with CMV who are otherwise healthy experience few if any symptoms. When first infected, some adults may have symptoms similar to mononucleosis, including fatigue, fever and muscle aches.

When to see a doctor

If you have a weakened immune system and you're experiencing what may be signs or symptoms of CMV infection, see your doctor. CMV infection in people with compromised immunity can be fatal. People who are immunocompromised because they have undergone bone marrow or organ transplants seem to be at greatest risk.

If you develop a mononucleosis-like illness while you're pregnant, see your doctor so that you can be evaluated for CMV infection. Talk to your doctor about the possible risks to your unborn baby if you have the virus.

If you have CMV but are otherwise healthy, and you're experiencing any mild, generalized illness, you could be in a reactivation period. Practical self-care steps, such as getting plenty of rest, should be enough for your body to control the infection. You probably don't need to see your doctor.

When your child should see a doctor

If you know you were infected with CMV during your pregnancy, let your baby's doctor know. Your doctor should follow your baby to ensure he or she has no vision or hearing problems. However, newborns who are well otherwise are unlikely to develop life-threatening disease later.

Cytomegalovirus is related to the viruses that cause chickenpox, herpes simplex and mononucleosis. Once you're infected with CMV, the virus remains with you for life, but it's not always active. CMV may cycle through periods during which it lies dormant and then reactivates. If you're healthy, it mainly stays dormant. You can pass the virus to others during reactivation.

Transmission of the virus occurs through exposure to body fluids — including blood, urine, saliva, breast milk, tears, semen and vaginal fluids — not by casual contact.

The virus can spread in a number of ways:

  • Touching your eyes or the inside of your nose or mouth after coming into contact with the body fluids of an infected person. This is the most common way CMV is spread because it's absorbed through the mucous membranes.
  • Through sexual contact with an infected person.
  • Through the breast milk of an infected mother.
  • Through organ transplantation or blood transfusions.
  • Through the placenta, from an infected mother to her unborn child, or during birth.

CMV is a widespread and common virus that can infect almost anyone. But healthy children and adults who contract the infection usually have few if any symptoms, so CMV often goes undiagnosed.

In the rare cases in which CMV causes a healthy person to become very sick, the infection may cause the following complications:

  • CMV mononucleosis. This syndrome resembles infectious mononucleosis, but the Epstein-Barr virus (EBV) causes classic mononucleosis. If you have signs and symptoms that resemble mononucleosis — a sore throat, swollen glands and tonsils, fatigue, and nausea — your doctor will test you for the antibody your body makes to fight off EBV. If it's absent, there's a chance CMV is causing your symptoms.
  • Intestinal complications. CMV infection in your intestines can result in diarrhea, fever and abdominal pain; inflammation of your colon; and blood in your stool.
  • Liver complications. CMV can cause abnormal functioning of your liver and an unexplained fever.
  • Nervous system complications. A variety of neurological complications have been reported as a result of CMV infection in the nervous system. These may include inflammation of your brain (encephalitis).
  • Lung complications. CMV can cause inflammation of your lung tissue (pneumonitis).

Complications arising from newborn CMV infection

Newborns with CMV can experience:

  • Hearing loss
  • Eye abnormalities, including central vision loss, scarring of the retina, an inflammation of the light-sensing layer of the eye (retinitis), and swelling and irritation of the eye (uveitis)
  • Mental disability
  • Lack of coordination
  • Small head
  • Seizures
  • Death

Careful hygiene is the best prevention against CMV. Health care workers have the greatest opportunity for exposure, but because of precautions used in the health care setting, their risk of acquiring the disease is low.

You can take these precautions to help prevent CMV infection:

  • Wash your hands often. Use soap and water for 15 to 20 seconds, especially if you have contact with young children or their diapers, drool or other oral secretions. This is especially important if the children attend child care.
  • Avoid contact with tears and saliva when you kiss a child. Instead of kissing a child on the lips, for instance, kiss on the forehead. This is especially important if you're pregnant.
  • Avoid sharing food or drinking out of the same glass as others. Sharing glasses and kitchen utensils can spread the CMV virus.
  • Be careful with disposable items. When disposing of diapers, tissues and other items that have been contaminated with bodily fluids, be careful not to touch your hands to your face until after thoroughly washing your hands.
  • Clean toys and countertops. Clean any surfaces that come into contact with children's urine or saliva.
  • Practice safe sex. Wear a condom during sexual contact to prevent spreading the CMV virus through semen and vaginal fluids.

Experimental vaccines are being tested for women of childbearing age. These vaccines may be useful in preventing CMV infection in mothers and infants, and reducing the chance that babies born to women who are infected while pregnant will develop disabilities. If you have a compromised immune system, you may benefit from taking antiviral medication to prevent CMV disease.

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